This is because the public sector debt..

Is out of control. Any sort of entrepreneurial mechanisms have been killed off by over-regulation and taxes due to the socialist state*. In essence we are running on a full tank of gasoline, but siphoning 70% of the gasoline off before it reaches the combustion engine. By the time it reaches the combustion stage, the output is marginal.

The welfare state has been a tremendous boondoggle that has not helped any of the sorts of people it has promised to help at all. It's enriched public administrators, much like in the old USSR, it's permitted the very wealthy to increase their wealth, through bailouts, during one of the most acute crashes in history. Now we have states that are enormous, interest rates at 5000 year lows, no usury laws, a nation of debt slaves through the education system etc.

The question is, whether the public debt can be rebalanced without a total collapse in order and civilization. Some regions might manage it, others won't.